V-ribbed belts are used in various technical areas, in particular as endless transmission belts. They are distinguished by the fact that, on its side facing the belt pulley, the belt has a plurality of ribs running longitudinally, which interact with a multi-grooved belt pulley. The number of ribs is greater than or equal to 2 and is generally between 3 and 10 V ribs. The force between belt pulley and belt is introduced via the rib flanks.
There are industrially standardized rib profiles. Here, the profiles PH, PJ, PK, PL, PM have overall belt heights between 2 and 15.0 mm with rib spacings between 1.6 and 9.4 mm. The rib heights are approximately between 1 and 9 mm.
In general, the ribbed belts have the structure usual for transmission belts, comprising the following zones:    1. the back of the belt or the expansion zone facing away from the belt pulley;    2. a load-bearing zone having tension carriers running, for example wound, in the circumferential direction, made of cables, cords or strips;    3. a substructure or a compression zone directed toward the belt pulley, on which the ribs for the engagement in the grooves of the belt pulley are formed.
Here, the entire belt body and in particular the substructure is composed of at least one high-performance elastomer, traditionally a rubber elastomer.
In order to improve the mechanical properties and the running performance of the belts, novel elastomer materials, which are frequently electrically non-conductive, are increasingly used nowadays. Electrostatic charging of the belt therefore occurs during running.
While a V-belt normally runs sunk in the individual groove of the associated belt pulley and thus has complete contact with the belt pulley at the sides, this is not the case in a V-ribbed belt, since the belt pulley engages in the interspaces between the ribs only frontally, so that the belt rests on the circumference of the belt pulley. The back of the belt and the tension carrier layer have no contact with the belt pulley in this case; the contact is produced exclusively via the rib flanks.
In the case of ribbed belts, it is therefore not possible to effect the dissipation of electrostatic charges via a conductive textile layer on the back of the belt. In addition, the complete sheathing of the ribbed belt with a conductive textile material is not feasible or reduces the belt quality considerably, because of the acute-angled valleys between the steep rib flanks. Complete coating or sheathing of the ribs additionally destroys the mechanical action of the high-performance elastomer lying underneath during the introduction of force.
WO 2009/16797 A1 discloses a ribbed belt, of which the ribbed elastomer contains short fibers and large-grained carbon distributed in point form. However, fibers and relatively large particles made of foreign materials have a detrimental influence on the mechanical-dynamic properties of the elastomer of the force transmission zone, so that this method cannot be the method of choice.